… which applies to all tracks.
The delay columns/tracks effects of individual tracks would then be relative to that “master delay”.
If everything is delayed equally, is there any sense in it?
Isn’t there pattern delay command that does exactly that? Oh, wait it delays by rows.
That’s a nice idea for a “global groove”… but is it intuitive enough?
Not any less intuitive than e.g. having to put a delay of 0x80 on every track every 4 lines.
Depends on how you use it 
Delay column for master track: good idea! Starshine time!
While you’re at it… master retrig kthx